PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "2008-01-29, Version 1.8" RECORD_TYPE = STREAM OBJECT = DATA_SET DATA_SET_ID = "CO-V/E/J/S-RADAR-3-LBDR-V1.0" OBJECT = DATA_SET_HOST INSTRUMENT_HOST_ID = CO INSTRUMENT_ID = RADAR END_OBJECT = DATA_SET_HOST OBJECT = DATA_SET_INFORMATION ABSTRACT_DESC = "N/A" ARCHIVE_STATUS = "ACCUMULATING" CITATION_DESC = "N/A" DATA_OBJECT_TYPE = TABLE DATA_SET_COLLECTION_MEMBER_FLG = "N" DATA_SET_NAME = " CASSINI ORBITER RADAR LONG BURST DATA RECORD" DATA_SET_RELEASE_DATE = 2018-03-22 DATA_SET_TERSE_DESC = " The Cassini Long Burst Data Record product contains instrument telemetry, calibrated science data, and time-sampled echo data from Cassini radar observations. " DETAILED_CATALOG_FLAG = "N" PRODUCER_FULL_NAME = "Philip S. Callahan" START_TIME = 1999-230T03:37:24.327 STOP_TIME = "NULL" CONFIDENCE_LEVEL_NOTE = " * Confidence Level Overview The burst ordered data products (SBDR, LBDR, and ABDR) contain all science data obtained by the Cassini RADAR instrument during the mission. A data record is obtained for each measurement cycle. This data is calibrated whenever a calibrated value obtained from a single measurement cycle is physically justified. This is always the case for close Titan flybys and seldom the case for other observations. * Review The data will be validated internally by the Cassini Radar Team prior to each release of data to the PDS. The overall data set organization will also be peer reviewed once by the PDS prior to the release of the first volume. * Data Coverage and Quality The following observations will be included in the SBDR and LBDR archives: 1) Close (1000-200000 km) Titan flyby observations 2) Distant Titan observations 3) Observations of Saturn and its rings 4) Observations of icy satellites 5) Radiometer observation of Jupiter 6) Sun scan observations used to calibrate antenna patterns 7) Earth swingby observation The SBDR contains one record for each active or passive measurement cycle but does not contain the sampled radar echo data or altimeter profiles. The LBDR includes only active mode measurement cycles. It contains sampled radar echo data but no altimeter profiles. The ABDR includes only altimeter measurement cycles. It contains altimeter profiles but no radar echo data. The ABDR-SUMMARY file is derived from the ABDR. It contains the estimated surface height and related measurements derived from the average of all pulses in a burst when the radar is in altimeter mode. SBDRs will be produced for all the observations mentioned above. LBDRs will be produced for close Titan flybys, the Earth swingby, and also some distant Titan and icy satellite observations whenever active mode measurements are obtained. ABDRs and ABDR-SUMMARY files will only be produced for close Titan flybys because this is the only time altimeter mode is employed. Three types of calibrated measurements are obtained: backscatter (scatterometer), antenna temperature (radiometer), and surface height (altimeter). The calibrated scatterometer values are normalized radar cross-section, a unitless quantity related to the slope, roughness, and composition of the observed surface. We currently estimate the accuracy of this quantity to be + or - 3 dB absolute and + or - 2 dB relative. We estimate the accuracy of the antenna temperature to be + or - 5 percent absolute and + or - 0.2 K relative. We estimate the accuracy of the surface height to be approximately + or - 100-200 m. Location error of the measurements is dominated by ephemeris and pointing knowledge errors and is expected to be less than 2 km throughout the mission. * Limitations Ephemeris error is expected to improve throughout the mission. Since there is no plan to recompute the ephemeris of previous observations as new measurements are obtained, however, earlier observations may have poorer location accuracy. The dominant backscatter calibration error term is error in our knowledge of the gain of the attenuators in the receiver. Engineering tests are currently planned to improve our knowledge of the attenuator gains. Besides ephemeris error, the main errors in the altimeter surface height determination come from off-nadir pointing and actual surface height variation with the altimeter footprint of diameter typically 25-50 km. " DATA_SET_DESC = " * Data Set Overview Burst Ordered Data Products (BODP) are comprehensive data files that include engineering telemetry, radar operational parameters, raw echo data, instrument viewing geometry, and calibrated science data. The BODP files contain time-ordered fixed length records. Each record corresponds to the full set of relevant data for an individual radar burst. The Cassini Radar is operated in 'burst mode,' which means the radar transmits a number of pulses in sequence then waits to receive the return signals. 'Burst' is a descriptive term for the train of pulses transmitted by the radar. The term 'burst' (somewhat unconventionally) refers to an entire measurement cycle including transmit, receipt of echo, and radiometric (passive) measurements of the naturally occurring radiation emitted from the surface. In fact, even when the transmitter is turned off and only passive measurements are made Burst Ordered Data Products are still fixed header length, fixed record length files. The header is an attached PDS label. Records are rows in a table. Each data field is a column. All one needs to know to read a particular data value from a particular data field is the header length, the record size, and the byte offset of the data field within the record. Since a UTC time tag is included in each record, it is a simple matter to restrict the data one reads to a particular time interval. The BODP comprise three separate data sets, including the Short Burst Data Record (SBDR), the Long Burst Data Record (LBDR), and the Altimeter Burst Data Record (ABDR). The only difference between the three formats is whether or not two data fields are included: the sampled echo data and the altimeter profile. The altimeter profile is an intermediate processing result between sampled echo data and a final altitude estimate. LBDRs include the echo data but not the altimeter profile. ABDRs include the range compressed altimeter pulse profiles but not the echo data. SBDRs include neither. These trivial differences necessitate different data sets because the two fields in question are much larger than all the other data fields combined. The majority of the bursts in a typical Titan pass are passive measurements. These bursts do not produce echo data or altimeter profiles. Of the active mode bursts most are not in altimeter mode so no altimeter profiles are produced. Including these two data fields when they are invalid would ridiculously increase the size of the archived data. The alternative of having variable length records was deemed to overly complicate data archiving and analysis procedures. Maintaining three data sets reduces data volume while allowing record lengths to remain fixed.The descriptions of each field in the records can be found in the LBDR.FMT, SBDR.FMT, and ABDR.FMT files. These files are located in the appropriate data directories (e.g., DATA/LBDR/LBDR.FMT ). They describe the size, type, and meaning of each field. The LBDR.FMT and ABDR.FMT files reference the SBDR.FMT files for all fields held in common by the three data sets. In order to further facilitate temporal segmentation of the data, the structure and time sequence of the data is described in the sequence design memo for the observation found in the EXTRAS directory. Each record in a BODP file is comprehensive and contains the acquisition time, viewing geometry, quality flags, and radar mode of the burst, so that data segmentation can be easily automated without resorting to the sequence design memo. An SBDR record is produced for every burst throughout the pass in an observation. An LBDR file is produced only for bursts during which the transmitter was on. (Sometimes it is necessary to create multiple LBDR files in order to avoid file lengths > 2 Gbytes which are problematic for older operating systems.) An ABDR file is produced only for periods in which the radar is in altimeter mode. If desired, bursts can be easily matched across data sets. One data field in each record is a burst identifier, which uniquely distinguishes a burst from all other bursts in the mission. Records in different data sets that correspond to the same burst have the same burst ID. The SBDR data record is divided into three consecutive segments from three different levels of processing: 1) the engineering data segment, 2) the intermediate level data segment (mostly spacecraft geometry), and 3) the science data segment (brightness temperature, backscatter, measurement geometry, etc.). The engineering data segment contains a complete copy of the telemetry data downlinked from the spacecraft. It includes temperatures, instrument instructions, operational parameters of the radar, and raw measurements (i.e., unnormalized radiometer counts.) For more information about the format and content of the SBDR, LBDR, and ABDR files, see the Cassini Radar Burst Ordered Data Product (BODP) Software Interface Specification, JPL D-27891. A copy of the document is located on this volume as file BODPSIS.PDF in the DOCUMENT directory. * Parameters A complete listing of the parameters can be found in the SIS. * Processing Cassini RADAR telemetry packets are transmitted to earth along with other spacecraft and instrument telemetry at the conclusion of each data take. The radar data packets are queried from the telemetry data system (TDS) on a computer in the radar testbed which has access to TDS. These packets are placed sequentially into a raw data file. The raw file is initially processed by radar software on the testbed computer which identifies radar science activity blocks (SAB) within the telemetry stream and reformats the data and provides some quick look displays and limit checking. The reformatted data file (L0) is delivered to the radar processing group for processing by Radar Analysis Software (RAS) and then the SAR Processor (SP, if applicable). Temperature telemetry files from the spacecraft are also queried from TDS and delivered to the processing group for RAS and SP to use. All other ancillary data is obtained from SPICE kernel files which are delivered by different elements of the project to an ftp site. These files are separately archived in the PDS system. The RAS pre-processor reads the radar L0 file, associated temperature telemetry files, and the SPICE kernel files and all relevant data are placed into the SBDR/LBDR engineering and intermediate level data segments. The science processors for radiometery, scatterometry, and altimetry, as well as SAR, ingest the SBDR/LBDR files and produce mode-specific science data products (and modify science data segment fields). Note that measurement geometry will not be available and will be flagged as invalid for cases in which there is no target body or the measurement extends beyond the limb of the target body. There is no plan to compute the science data segment for non-Titan bodies with the exception of radiometric observations of Saturn and its rings. For other bodies these fields will be flagged as invalid. For most non-Titan icy satellite observations, due to SNR effects, only a single brightness temperature or backscatter measurement will be computable rather than values for each burst. For these observations a single backscatter value and a single antenna temperature value will be reported in the AAREADME.TXT file in the root directory of the volume. Sometimes a short list of backscatter values will be reported as a function of frequency of the returned echo. * Data See Parameters. * Ancillary Data There are no ancillary data needed to use the LBDR. * Coordinate System Data locations for each record are computed from Project SPICE kernels. Measurement geometry information is available for both the active and passive mode measurements. Some of the active and passive mode quantities are likely to be identical (e.g., polarization orientation angle). However, separate data fields are reported, because the differences in the passive and active mode measurement times can in principle cause the two cases to differ. Passive geometry is computed for the time corresponding to the midpoint of the passive receiver window (summed radiometer windows). Active mode geometry is computed for the time halfway between the midpoint of the transmission and the midpoint of the active mode receiver window. The full set of measurement geometry for each case includes the polarization orientation angle, emission/incidence angle, azimuth angle, the measurement centroid, and four points on the 3-dB gain contour of the measurement. The centroid and contour points are specified in latitude and longitude, using the standard west longitude positive geodetic (planetographic) coordinate system sanctioned by the IAU. The geodetic part of the definition is moot since Titan is modeled by a sphere. The measurement geometry will not be available and will be flagged as invalid for cases in which there is no target body or the measurement extends beyond the limb of the target body. * Software No software is provided within this volume. * Media/Format The data are provided on media as determined by PDS. The main data files are ZIPPED as described in the PDS standard. Detached labels are provided for the ZIPPED files. The ZIPPED files also include their attached labels. Other formats are defined within the attached labels of the files. " END_OBJECT = DATA_SET_INFORMATION OBJECT = DATA_SET_MISSION MISSION_NAME = "CASSINI-HUYGENS" END_OBJECT = DATA_SET_MISSION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "ELACHIETAL2005" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "ELACHIETAL2004" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_TARGET TARGET_NAME = EARTH END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = ENCELADUS END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = IAPETUS END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = PHOEBE END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = RHEA END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = TETHYS END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = HYPERION END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = DIONE END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = MIMAS END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = SUN END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = TITAN END_OBJECT = DATA_SET_TARGET END_OBJECT = DATA_SET END